Remove room database on app uninstall

问题

I am making an app and I am using Android Room Persistence Library to handle my database layer. Room Library works like charm and everything is fine with it. But I want the database that room creates to be removed when the user uninstall the app. I tried uninstalling the app and then installed again, but somehow the database was still there and app was able to get the old data from it.

I thought maybe because my app data backup is set to auto in the settings and android is backing it up on cloud and bringing it back again but turning off backup from settings didn't help. Even if that worked that doesn't sound like a good solution to me.

I have created a very simple class that extends RoomDatabase and below is the code if that helps answering the question.

I know that I can use fallbackToDestructiveMigration() on the database builder and increase the database version. It will clear the data from the database. That is not what I want.

@Database(entities = {UnleashedEntity.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {

    private static AppDatabase INSTANCE;

    public abstract DaoContract MyDao();

    public static AppDatabase getAppDatabase(Context context) {
        if (INSTANCE == null) {
            INSTANCE =
                    Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, "user-database")
                            .build();
        }
        return INSTANCE;
    }

    public static void destroyInstance() {
        INSTANCE = null;
    }
}

Edit I know I can use ACTION_PACKAGE_REMOVED intent to make my app aware of the uninstall. What I wanted to know, Is there a configuration of the databasebuilder that does the job, and How come the database persists after app uninstall.

回答1:

Is there a configuration of the databasebuilder that does the job

AFAIK room does not know about app getting uninstall so Room probably won't wipe the database for you on uninstall.

How come the database persists after app uninstall

Beginning with Android 6.0 (API level 23), Android offers the Auto Backup feature which is enabled by default. According to the documentations, it backup the following to google drive:

Shared preferences files.
Files saved to your app's internal storage, accessed by getFilesDir() or getDir(String, int).
Files in the directory returned by getDatabasePath(String), which also includes files created with the SQLiteOpenHelper class.
Files on external storage in the directory returned by getExternalFilesDir(String).

This backup your room database too.

How to disable auto backup

In your manifest:

<manifest ... >
    ...
    <application android:allowBackup="false" ... >
        ...
    </application>
</manifest>

回答2:

Make your App Uninstall aware like described in this answer from AnniJais.
Make a method in the Dao with the @Query Annotation that deletes the Database.

@Query("Drop Database myDatabaseName")
public void nukeDatabase();

Call your Dao method in the part previously added:

if (activityName.equals("com.android.packageinstaller.UninstallerActivity")) { // User has clicked on the Uninstall button under the Manage Apps settings

Step 2 is not really testet of me.

来源：https://stackoverflow.com/questions/49677497/remove-room-database-on-app-uninstall

标签

android

android-room